The beltway was constructed in a clockwise fashion beginning at
Leverkusen. In 1936 the section between Leverkusen and
Cologne-Mülheim was built as a component of the Autobahn
Oberhausen-
Wiesbaden and in 1937 the section to
Siegburg was finished. Thus today's
Ostring (East-Ring) was drivable at that time. In 1941, the
Rodenkirchener Autobahnbrücke was completed and the connection between the
A 3 and the Autobahn to
Bonn (today
A 555) was established. From 1957 to 1960 the Autobahn Cologne-
Aachen was finished and the section from
Kreuz Köln-Süd to the later
Kreuz Köln-West was put into service in 1958. Construction of a second
Autobahn-bridge across the
Rhine in the north of Cologne began in 1961. At its completion, the beltway could be used along its entire length. In 1971, the A 1 was extended to the south beyond the
Köln-West interchange and in 1974 the A 4 was connected to the A 3 from the east at the
Köln-Ost interchange. Since then, the section between interchanges
Kreuz Köln-Ost and
Dreieck Heumar consists of two Autobahns, the A 3 and the A 4. == Current state ==